Electric-arc lamp



(No Model.)

- E. THOMSON.

ELECTRIC ARC LAMP.

Patented Apr. 26, 1898.

Wink-.5555.

UNITED STATES PATENT OrricE.

ELIHU THOMSON, OE SXVAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NElV YORK.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 602,922, dated April 26, 1898.

Application filed November 4, 1897. Serial No. 667,434. (No model.)

4 circuits in which the expansion and contraction of a wire through which the current of a lamp passes regulates the feed and ad justment of the movable carbon.

The object of this invention is to render the action of such a lamp very precise and delicate; and this is effected by combining with the expansion-wire an electromagnet responsive to the current of the lamp and which shunts more or less current into or from the expansion-wire.

The accompanying drawing shows in elevation a portion of an electric-arc lamp embodying this invention.

Supported in and extending through a suitable frame A is the vertically-movable rod B, to the lower end of which is secured by a suitable clamp b the upper carbon C, the lower fixed carbon 0 being secured to the base 0 of the lamp by a suitable clamp d, as shown. A side tube D, secured at its lower end to the base a and at its upper end to the frame A, contains the expansion-wire E in circuit with the lamp and carries the current which passes through the carbons back to the negative terminal t, where the current is a continuous or direct current, or to one of the terminals where the current feeding the lamp is alternating. The positive or second terminal is shown at t, connected by contact 0 to the rod B. Any suitable clutch or releasing detent gear may be used for regulating the position of the upper or movable carbon. As here shown, a suitable clutch F is employed having a lever-arm E, controlled by spring f and stop f, mounted on frame A. The clutch F when raised lifts the rod B and when lowered releases it. v

To a bracket G on frame A is fulcrumed one end of a lever 9 and on the other end of lever g is hinged the upper end of a rod g, secured at its lowerend to clutch F. Also fulcrumed to bracket G, below lever g, is a lever h, hinged to expansion-wire E and connected at its outer end by a link 7t to lever g. Aspring 2', depending from a suitable support and, as here shown, from the coil j of an electromagnet H, is connected to lever g. The clutch F is lifted by lever g, which in turn is lifted by sprin g t.

In carrying out the present invention an electromagnet is located in series in the circuit of the lamp between terminals 25 and 25. As shown, it is placed between the wire E and the terminal '6. The electromagnet H may be made in the form of a solenoid. Upon or connected with the core H is mounted a contact 6, carried upon the outer end of a spring or flexible arm 7', secured at its inner end toa bracket 7' on the frame A. The contact 6 bears against the outer end of a flexible contact-arm K, mounted on bracket 9' The contact e is operated by the electromagnet II, the core H of which tends to enter the coil when the current is on and which tendency may be in a measure balanced by the spring j, the Contact 6' making and breaking contact with the flexible contact 7c. In circuit with contact c is placed a resistance 7*, which, when the contact 6 is closed, acts as a shunt around the wire E, cutting a certain proportion of current out of or around it.

The circuit at contact 6 opens when the cur-. rent through the are and magnet H exceeds the normal and is closed when the current is below normal. he contact 6, therefore, intermittently opens and closes the shunt-circuit around wire E. lVhen the contact 0 opens, the shunt through the resistance 1' is opened and all the current passes through wire E, which expands and permits the spring 2' to raise lever g, rod 9, clutch F, and with the latter rod B and carbon C, thereby lengthening the arc. Lengthening the are when the lamp is run on a branch circuit from constantpotential mains with a resistance in the circuit weakens the current and brings it to the normal. As the carbons, however, consume the arc becomes too long, the current weakens,the electromagnet H becomes weaker,and the contact a is closed, thereby putting the resistance r as a shunt around the wire E.

The wire E, receiving less current, cools, shrinks, and draws down the lever h and lever pulling down rod g and releasing clutch F, thereby releasing rod 13 and permitting carbon C to descend and shorten the are. The sensitiveness of the feeding action then is not dependent upon the variations of temperature of the wire E when current is passed through it, butis dependent upon the strength of the electromagnet H, which governs the flow of current through the wire E.

The contact a may be made either a variable-resistance contact or a set of contacts opening in succession with proper shunting resistance, and the control will thereby be made more delicate. I find that for all practical purposes a simple contact 6, which I prefor to make of pure silver, with a resistance r, properly adjusted, is suflicient, especially when the magnet-core II is made small and light, so as to be readily responsive and so as to vibrate the contact a slowly, whereby the flow of current in wire E is kept at just that amount which makes the normal are.

It will be understood that any other form of thermo-electric expansive device may be used in lieu of wire E, such as several wires or compound bars or other responsive thermal arrangement, and that the clutch F may be replaced by any other feeding mechanism, giving more or less rapid feeding movement to the upper carbon than would be given by the ordinary clutch, the essential feature of the present invention being the control of the heating effect of the thermo-electric expansive device, not by the variations of current flowing in the lamp when the hot wire is preserved constantly in the lam p-circ uit, as heretofore, but by such variations of current as are set up in response to still smaller variations in the electromagnet-controlling arrangementthat is, the electromagnet being sensitive to slight departures from the normal current produces in the hot wire or other thermo-electric expansive device an accentuation of the effect of current variations and provokes the working of the regulator when otherwise it would be practically inert.

WVhat I claim as new, and desire to secure by Letters Patent of the United States, is

1. In an electric-arc lamp, the combination with carbon-feeding mechanism, of a thermoelectric expansive device, and a series electromagnetic controlling apparatus, responsive to variations in the current passing through the lamp governing the operation of the thermo-electric expansive device, as set forth.

2. In an electric-arc lamp, the combination, with carbon-feeding mechanism, of a thermoelectric expansive device, an electromagnetic controlling apparatus in series therewith, and a resistance acting as a shunt to the thermo electric expansive apparatus, the whole being so arranged that the electromagnet controls the circuit of the expansive device and of the shunting resistance.

3. In an electric-arc lamp, the combination with the carbon-feeding mechanism, of an expansion-wire connected therewith, an electromagnet in the lamp-circuit, yielding contacts, one of which is connected to the core of said electromagnet, and a resistance, the whole being so arranged and connected that in one position of the core of the electromagnet and contacts controlled thereby, the expansion-wire is included in circuit, but in a second position shunted by said resistance, as set forth.

' 4. In an electric-arc lamp, a carbon-c1 utch, a thermo-electric expansion-wire, a springcontrolled mechanism connecting said wire with said clutch for raising and lowering the latter, an electromagnet, a pair of springcont-acts normally closed, one of which is connected to the core of the electromagnet, and a resistance acting as a shunt to the expansion-wire, the whole being so arranged that the electromagnet controls the circuit of the expansion device of the shunting resistance.

5. The combination in an electric-arc lamp, of a carbon-feeding mechanism, a hot wire or equivalent expansion device for regulating the action of the feeding mechanism, and means arranged in series with and intermittently opening and closing the circuit of the expansion device upon comparatively small changes of the current in the lamp-circuit from the normal value, as set forth.

6. In an electric-arc lamp, the combination of a feeding mechanism, an expansion-conductor or equivalent device for regulating the action of the feeding mechanism, and means for automatically regulating or controlling the circuit of the expansion-conductor arranged in series with the expansion device so as to augment or intensify the variations of current in the expansion-conductor in comparison with variations of current in the lamp-circuit.

'7. The combination in an electric lamp, of a feeding mechanism, an expansion-conductor or equivalent device for regulating the feeding mechanism, an electromagnet in series with the expansion-conductor, and a circuit controlling or changing device under control of said magnet and serving to intensify the variations of current in the expansion-conductor in comparison with the current changes in the magnet, as set forth.

In witness whereof I have hereunto set my hand this 2d day of November, 1897.

ELII'IU THOMSON. lVitnesses:

JOHN W. GIBBONEY, W. MUNVALLO.

IIO 

